The design of internal combustion engines used in motor vehicles is primarily based upon the use of reciprocating pistons. The pistons are located in cylinders and move up and down in the cylinders. When the pistons are near the top of the cylinders, a small amount of fuel is injected into the top of the cylinder above the piston and is ignited by compression and/or a spark. The ignition of the fuel causes the gas above the piston to expand rapidly to assist the piston in its downward stroke. The pistons are connected to a crankshaft via a piston rod. The crankshaft rotates and provides the force to drive the engine.
It is well recognised that this type of engine is very inefficient, partly because so much of the energy generated from the ignition of the fuel is used in the reciprocating motion of the pistons. The reciprocating motion also limits the speed that the engine can achieve. For example, such an engine can generally only achieve a maximum of about 18,000 rpm. As a result of the inefficiencies of this engine, its size cannot be reduced without compromising the power of the engine.
Whilst it has been known for some time that a rotary engine would be more efficient than a normal piston engine as described above, a successful purely rotational engine has not been achieved. This is because, all prior rotary engines:
(i) still involve at least partially reciprocating movement which as described above results in inefficiency;
(ii) fail to incorporate readily sealable chambers capable of withstanding the pressures generated at working load; and/or
(iii) fail to provide for compression and combustion to occur in a common zone.